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Neuron. 2018 Mar 7;97(5):1063-1077.e4. doi: 10.1016/j.neuron.2018.01.048. Epub 2018 Feb 22.

The Sixth Transmembrane Segment Is a Major Gating Component of the TMEM16A Calcium-Activated Chloride Channel.

Author information

1
Departments of Physiology, Biophysics and Biochemistry, University of California, San Francisco, San Francisco, CA 94158, USA. Electronic address: christian.peters@ucsf.edu.
2
Departments of Physiology, Biophysics and Biochemistry, University of California, San Francisco, San Francisco, CA 94158, USA.
3
Department of Pharmaceutical Chemistry and Cardiovascular Research Institute, University of California, San Francisco, San Francisco, CA 94158, USA.
4
Departments of Physiology, Biophysics and Biochemistry, University of California, San Francisco, San Francisco, CA 94158, USA; Howard Hughes Medical Institute, University of California, San Francisco, San Francisco, CA 94158, USA.
5
Departments of Physiology, Biophysics and Biochemistry, University of California, San Francisco, San Francisco, CA 94158, USA; Howard Hughes Medical Institute, University of California, San Francisco, San Francisco, CA 94158, USA. Electronic address: lily.jan@ucsf.edu.

Abstract

Calcium-activated chloride channels (CaCCs) formed by TMEM16A or TMEM16B are broadly expressed in the nervous system, smooth muscles, exocrine glands, and other tissues. With two calcium-binding sites and a pore within each monomer, the dimeric CaCC exhibits voltage-dependent calcium sensitivity. Channel activity also depends on the identity of permeant anions. To understand how CaCC regulates neuronal signaling and how CaCC is, in turn, modulated by neuronal activity, we examined the molecular basis of CaCC gating. Here, we report that voltage modulation of TMEM16A-CaCC involves voltage-dependent occupancy of calcium- and anion-binding site(s) within the membrane electric field as well as a voltage-dependent conformational change intrinsic to the channel protein. These gating modalities all critically depend on the sixth transmembrane segment.

PMID:
29478917
PMCID:
PMC5860880
DOI:
10.1016/j.neuron.2018.01.048
[Indexed for MEDLINE]
Free PMC Article

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